The Importance of Soil Testing in Erosion Control Projects

Soil erosion is an issue of global importance with approximately 25-30 Gt of soil per year lost. While some erosion is naturally occurring, activities like construction can cause erosion. It is imperative that construction sites are reviewed to create plans for erosion and sediment control that are tailored to the specific sites.

One of the most effective Best Management Practices is to establish vegetative cover that is adapted to the site’s geographic region and environmental conditions. Unfortunately, the physical and chemical characteristics of the soil are often neglected when creating these plans. In most cases, steps will need to be taken to ameliorate soil deficiencies or excesses in order to successfully germinate seedlings and establish sustainable cover.

Examining almost 12,000 soil samples from erosion control projects, testing has exposed several common issues that need to be addressed. Aside from moisture, the two most important soil characteristics to consider are pH and OM. For pH, samples had a range of 2.1 to 12.4 with only 32% within the ideal range of 6.3-7.3. With OM, only 8% of samples were higher than the ideal 5% OM. These numbers illustrate the need for soil sampling to identify deficiencies or toxicities as well as finding ways to address soil issues prior to seeding. If vegetation cannot be established to the specified density and the requirements for Notice of Termination are not met, subsequent applications and treatments may be needed.

This presentation will delve deeper into the referenced soil test analytics and offer recommendations for basic amelioration using actual project examples. In addition, guidance on development of soil test specifications, their implementation, inspection and maintenance will also be provided.